DESCRIPTION (Adapted from Applicant's Description): The major objective of this project is to utilize transgenic technology to develop immortalized granulosa cell (GC) lines which will maintain functional Follicle-stimulating hormone receptor (FSHR). In pilot studies, the investigators prepared a FSHR gene-promoter-SV40-T-antigen cDNA construct which targeted T-antigen (Tag) mRNA expression specifically to the gonads of the F1 mice. Their rationale is based upon the transgenic approach of Windle et al (Mol Endo 4:597,1990) in which LH alpha-subunit gene promoter-SV40-T-antigen cDNA constructs produced anterior pituitary tumors, from which immortalized LH-secreting cell lines were derived. They propose to develop FSHR-expressing GC lines in the same manner, but have extended the approach to the F2 generation because GC tumors did not develop in their hemizygous F1 offspring. The objectives will be to: 1) accelerate the development of tumors in the homozygous mice by neonatal DES treatment; and 2) develop and characterize GC lines from the Tag-induced and/or DES-Tag-induced ovarian tumors in terms of FSHR expression and responsiveness. FSHR- expressing cells will provide a powerful tool to study folliculogenesis at the molecular level. Their availability may allow the investigators in an expanded application to determine the mechanism(s) by which the pathways of mitosis and apoptosis in GC are uniquely regulated by FSH. They may also provide a critically important resource for molecular biological studies of ovarian cellular function.